Beu: Evolution of Janthina and Recluzia 
155 
Australian Bight. The lower member accumulated during a 
period of sea-level rise, in no more than 10 m of water, on 
shallow near-shore beds of the seagrass Amphibolis , during 
a period slightly warmer than at present. The upper member 
was deposited during a period of regression in a series of 
adjacent intertidal sand flat, beach, and supratidal lacustrine 
environments. The abundant specimens of Janthina chavani 
are all from the lower member and represent rafts of 
specimens cast ashore during periods of persistent onshore 
winds. They probably lost their floats through wave action 
and were deposited a short distance from the beach. All 
specimens observed are spectacularly well-preserved, 
although a few are slightly incomplete and none retains 
the protoconch. Roe Calcarenite evidently was deposited 
under the influence of the warm Leeuwin Current and its 
fauna includes several species of, for example, Cypraeidae 
and Volutidae that live further north in Western Australia at 
present. The faunas of Jemmys Point, Memana and Cameron 
Inlet Formations in Gippsland and Bass Strait reveal much 
lower water temperatures at their times of deposition than 
those affecting Roe Calcarenite, apparently at least partly 
explaining their lack of Janthina fossils. 
An important Australian record for confirming the time 
ranges of Janthina species is the abundant material of 
Janthina chavani recorded from Point Ellen Formation 
at Point Ellen, Vivonne, Kangaroo Island, and in a small 
remnant of the same formation at Cape Jervis, southern 
tip of the Fleurieu Peninsula, on mainland South Australia 
opposite Kangaroo Island (Ludbrook in Milnes et al ., 1983: 
28; Ludbrook, 1983: 45, figs 3h-j; Ludbrook, 1984: 232, 
figs 57o-p). Ludbrook (1983, 1984) correlated Point Ellen 
Formation directly with Roe Calcarenite because J. chavani 
is abundant in both units, but in no others. Therefore, she 
dated it as early Pleistocene, the age she assigned to Roe 
Calcarenite (Ludbrook, 1978). However, now that Roe 
Calcarenite is recognized as late Piacenzian (late Pliocene), 
no other formations on Kangaroo Island are dated as late 
Pliocene, and no other indicators of an early Pleistocene 
age are present in Point Ellen Formation, it is concluded 
here that Point Ellen Formation also is late Piacenzian in 
age. As the underlying unnamed Pliocene limestone at Table 
Rock contains specimens identified cautiously by Ludbrook 
(in Milnes et al., 1983: 23) as “what might be” Hartungia 
dennanti dennanti (i.e., J. typica ), this succession helps 
confirm the age ranges of Janthina species determined in 
New Zealand. 
Thanks to the life-long devotion of the late George 
Kendrick (formerly of WAM), several complete specimens 
and many recognisable fragments of Janthina chavani 
also have been collected from cuttings from water wells 
in the Perth Basin in Western Australia. They are limited 
to the “lower” Ascot Formation, of late Piacenzian age, 
and have not been collected from the overlying “upper” 
Ascot Formation. Mallett (1982) reported a late Pliocene 
form of the diagnostic early Pleistocene index foraminifer 
Globorotalia truncatulinoides (d’Orbigny) from the 
“Jandakot beds”, i.e., “lower” Ascot Formation, in wells 
around Jandakot in the Perth Basin, in samples supplied 
by Kendrick (base Pleistocene was defined at that time 
at 1.81 Ma, rather than the present 2.59 Ma). James et al. 
(2006: 414) used amino acid racemization ratios to correlate 
the “lower” Ascot Formation with the Roe Calcarenite, a 
correlation that seems reasonable from their containing the 
same Janthina species. However, the several late Pliocene 
deposits in widely separated areas of southern Australia 
each likely represent a short period of late Pliocene time, 
and possibly each was deposited during a single interglacial 
period. This includes “lower” Ascot Formation around 
Perth, Roe Calcarenite, Point Ellen Formation, and the 
laterally equivalent Norwest Bend Formation in the Murray 
River succession. There is ample time for them all to have 
subtly different ages during this period when shallow-water 
sedimentation was dominated by 41-ka sea-level cyclicity. 
Hallett Cove Sandstone was deposited during at least two 
distinct 41-ka cycles, and Bridgewater Limestone clearly 
was deposited during many or all 41-ka and 100-lea cycles 
during the last 2 m yrs. Australian successions help confirm 
a Messinian-early Piacenzian age range for J. typica and 
a late Piacenzian-Gelasian age range for J. chavani, with 
origination of J. chavani at c. 3.0 Ma. However, apart from 
in Bridgewater Limestone, Janthina fossils have not been 
recorded from marine rocks younger than late Piacenzian 
in southern Australia. Aminostratigraphy indicates that 
Bridgewater Limestone containing J. chavani extends up to 
at least late Calabrian in age. Bridgewater Limestone dune 
ridges in the region extending from inland of Naracoorte 
southwest to the coast of South Australia southeast of Robe 
potentially could provide a detailed history of the evolution 
and time ranges of the younger species of Janthina. 
The succession in Japan. Rather few fossil specimens 
of Janthina have been collected in south-eastern Japan 
(Figs 20-21). Hartungia elegans Tomida & Nakamura, 
2001 was based on specimens with spiral folds over the 
entire teleoconch. These specimens are interpreted here as 
having a low, wide, medially keeled shape and a flattened 
spire as a result of severe post-mortem compaction, and 
are reidentified as Janthina typica. Hartungia elegans 
was recorded from Senhata Formation, Miura Group, at 
Okumotona, Chiba Prefecture, Boso Peninsula, near Tokyo, 
Honshu, and from Tano Formation, Miyazaki Group, at Tano, 
Miyazaki Prefecture, Shikoku. Both localities were assigned 
to planktonic foraminiferal zone N17 (late Miocene, late 
Tortonian-mid-Messinian) (Tomida & Itoigawa, 1986: 116, 
fig. 1; Tomida, 1989; Ozawa & Tomida, 1992; Nakamura 
et al., 1999; Tomida & Nakamura, 2001). Some of the 
Japanese material identified as Parajanthina or Hartungia 
japonica Tomida & Itoigawa, 1982, of latest Miocene- 
early Pliocene age (late Messinian-Zanclean, planktonic 
foraminiferal zones N18-20; Hilgen et al., 2012: fig. 29.10) 
also has spiral folds over the entire teleoconch, including 
the sutural ramp. This material, also, is reidentified here as 
less severely compressed specimens of J. typica. Tamari 
Formation, Sagara Group, zones N18-19, late Messinian- 
early Zanclean, at Tamari, Kakegawa City, Shizuoka 
Prefecture (Tomida & Itoigawa, 1982: 62, fig. IB); Abina 
Formation, Kakegawa Group, Shimokurasawa, Kakegawa 
City, Shizuoka Prefecture, andUkari Formation, Kakegawa 
group, at Nito, Kakegawa City (Nobuhara, 1993; Nobuhara 
et al., 1995); and Osozawa Member of Akebono Formation, 
Shizukawa Group, also zone N18, at Osozawa, Yamanashi 
Prefecture (Tomida, 1996). The youngest material identified 
as H. japonica, from planktonic foraminiferal zones N21-22 
(late Piacenzian-Calabrian and younger; Hilgen etal., 2012: 
fig. 29.10) has weaker spiral sculpture, lacking folds on the 
sutural ramp, and although most specimens are relatively 
